The present invention relates to an automatic exposure control device for use with a camera, and in particular relates to an automatic exposure control device which can selectively accomplish either the aperture dominant or the shutter dominant type of automatic exposure control operations.
In the so-called automatic exposure control operation of the shutter speed dominant type (hereinafter referred to as "EE mode operation") wherein the aperture level of a photographic lens system is automatically controlled in response to the brightness of an object, the sensitivity of the film and the set exposure time, it is possible to take into consideration the motion of the object in deciding on the shutter speed. However, in EE operation the depth of field is constrained to follow the result coming from the aperture level of the photographic lens system which is determined automatically by the EE operation device used. Thus, EE mode operation is not completely satisfactory, because the depth of field is the most important picturing element in the case where the object is a still article.
On the other hand, a contrary situation exists for the so-called "automatic exposure control operation of the aperture dominant type" (hereinafter referred to as "ES mode operation") wherein the exposure time of a shutter is automatically controlled in response to the brightness of an object, the film sensitivity and the set aperture level of the photographic lens system. A defect, however, is that an excessive exposure time may be imparted to an object of swift motion, because the selection of shutter speed is not left to a photographer.
In the so-called "automatic exposure control operation of the programmed type" (hereafter referred to as "ES-EE mode operation"), wherein the predetermined combination of the aperture level and the exposure time is automatically controlled as a result of the brightness of an object and the film sensitivity, consideration is taken neither for swiftness of motion of the object nor for the depth of field but only for affording a proper exposure.
As will be apparent it is not possible to expect satisfactory results for all cases if the automatic exposure control operation is one of the three conventional methods mentioned above.